US 3210905 A
Description (OCR text may contain errors)
1965 c. J. GERLACH 3,210,905
APPARATUS FOR PACKAGING PERISHABLE ARTICLES Filed Sept. 10, 1962 2 Sheets-Sheet l INVENTOR CARL J. GERLACH ATTORNEY Oct. 12, 1965 c. J. GERLACH APPARATUS FOR PACKAGING PERISHABLE ARTICLES 2 Sheets-Sheet 2 Filed Sept. 10, 1962 INVENTOR CARL J. GERLACH ATTORNEY @(INNO ON N United States Patent 3,210,905 APPARATUS FOR PACKAGING PERISHABLE ARTICLES Carl J. Gerlacll, Green Bay, Wis., assignor to FMC Corporation, San Jose, Calif., a corporation of Delaware Filed Sept. 10, 1962, Ser. No. 222,475 4 Claims. (Cl. 53112) This invention relates to the art of packaging and pertains more particularly to methods of and machinery for displacing air within a wrapping by an inert gas so as to surround the wrapped article or material with a protective atmosphere.
Many perishable products are marketed at present in packages formed by wrapping flexible, gas-impervious sheet material around the product and exhausting air from the packages so as to reduce the tendency for the product to deteriorate by oxidation. Food products such as cheese and sliced meats are typical of the products benefited by this type of packaging.
A recent development in this field involves the replacement of air within the packages by an inert gas, e.g., nitrogen, thus to further contribute to the preservation of the fresh condition of the product by creating within each package a condition conducive to preservation of the original moisture content of the product. Known methods of replacing air within the package by an inert gas involve the use of an elongate tube for conducting the gas into the partially completed packages so as to effect discharge of the gas in a region adjacent a closed end of the package. This creates a backward flow of the gas within the wrapping so as to force much of the air through the opposite open end thereof, the inert gas taking the place of the air thus removed and thereby maintaining a gas pressure within the partly completed package at least as high as that of the ambient atmosphere. When the open end of the package is subsequently closed, some pressure of the entrapped preservative gas is maintained, if, in fact, it is not actually increased slightly as a consequence of the inward folding of the wrapper parts by which the package end is closed. Therefore, instead of producing a package in which the wrapped product is exposed to a partial vacuum having a tendency to withdraw moisture from the product, this method of packaging not only removes most if not all of the oxygen apt to effect spoilage of the product, but it also creates a condition of at least atmospheric pressure within the package which is beneficial to both the quality of the product when it reaches the consumer and the appearance of the package because it minimizes the tendency toward the formation of a greasy appearing film of moisture on the inside surface of the wrapper, which usually is transparent.
The use of an elongate tube reaching into the partly completed package so as to inject the inert gas thereinto and create the desired backward flow of the purging gas toward and out through the open end thereof has been found to be disadvantageous for several reasons. This is particularly true when the so-called gas purge method of wrapping is performed in automatic machinery which forms the packages by folding a continuously advancing web of wrapping material around a sequence of articles to be Wrapped advancing at the same speed as the wrapper web. Such automatic, continuous operation involves the use of a tubular former to one end of which the sheet of wrapping material is constantly supplied and around or Within which the wrapper is folded as it progresses toward the opposite end of the former, to bring the lateral edges of the wrapper sheet together. Thus the wrapper is formed into an axially moving hollow tube into which the articles to be wrapped are inserted by being fed into the receiving end of the former and advanced through the former to emerge from the opposite end thereof after having been enfolded within the web of wrapping material. Subsequently, the wrapper tube, with the spacedapart articles therewithin, progresses through a longitu dinal seal forming mechanism where the lateral edges of the web are sealed together, and through a transverse sealing mechanism which collapses and transversely seals the wrapper tube between each two articles, or between each two groups of articles if more than one article is to be contained within each package. The thus fully formed packages may be severed from each other along the transverse seals either simultaneously with the formation of the transverse seals or subsequently by means of a separate sealing devive. The United States patent to S. J. Campbell, No. 2,602,276, discloses an automatic wrapping machine which operates in this manner.
In order to incorporate the gas flush principle with an automatic wrapping machine of this nature, it has heretofore been the practice to extend the gas supply tube into the tube of wrapping material to discharge the gas therewithin in a region adjacent the transverse seal so as to obtain the longest practical reverse flow of the gas through the wrapper tube, and consequently relatively high efficiency in sweeping the entrapped air from around the entubed articles and out through the open end of the wrapper tube. This necessitates extending the gas supply tube through the web folding die so that in forming the wrapper into a tube, the die folds the wrapper around the gas supply tube as Well as around the articles being wrapped. Consequently the resulting wrapper tube is inevitably somewhat larger in cross-section than necessary to accommodate the articles alone and the wrapping of the ultimate package fits its contents less tightly and is less attractive than might otherwise be the case. Additionally, the presence of the gas supply tube in close proximity to the inner face of the wrapper tube and to the articles entubed therein, if not, in fact, in actual sliding contact therewith, complicates the matter of maintaining sanitary conditions within the wrapper tube and the packages formed therefrom and of avoiding scratching, abrading and otherwise harming the attractive appearance of that face of each article which is closest to the gas supply tube during passage of the article along the length of the gas supply tube.
The present invention seeks to incorporate the gas flush principle with automatic wrapping machinery in a manner retaining the desirable features of gas flushing but without the undesirable aspects thereof.
An object of the present invention therefore is to provide an improved method of wrapping articles.
Another object of the invention is to provide an improved wrapping machine including apparatus for performing the method of the invention.
Another object is to provide an improved method of, and an improved apparatus for, displacing air from within the wrapping of a package containing a perishable commodity.
Another object of the invention is to provide an apparatus for introducing an inert gas into the wrapper tube in process of formation in an automatic wrapping machine which is entirely clear of the wrapper tube forming die and which adds significantly to the appearance and hence to the saleability of the ultimate packages by avoiding contact with the articles at any time and by enabling formation of a Wrapper tube in the precise size which fits the wrapped articles closely.
Other objects and advantageous features of the present invention will become apparent from the following description and the drawings in which:
FIGURE 1 is a diagrammatic perspective of the packaging apparatus of the present invention.
FIGURE 2 is a diagrammatic longitudinal vertical section of the packaging apparatus of FIGURE 1.
FIGURE 3 is an enlarged transverse section on lines 3-3 of FIGURE 2.
FIGURE 4 is an enlarged transverse section on lines 4-4 of FIGURE 2.
The automatic wrapping machine (FIGS. 1 and 2) chosen for description herein as an example of the type of apparatus with which the gas injection device of the present invention can be combined advantageously is that constituting the subject matter of the above-mentioned Campbell patent, No. 2,602,276. In the present disclosure, only those parts of the wrapping machine are shown and described whose arrangement and operation must be understood in order to comprehend the method and apparatus of the present invention, since reference may be had to said Campbell patent for a complete description of the wrapping machine 10. Since the invention is particularly adapted for use in the wrapping of perishable items such as articles of food. The articles shown in FIGURES 2 and 3 being wrapped in the machine 10 are loaves 12 of cheese. It is to be understood, however, that it is within the purview of the present invention to employ it in the wrapping of other articles which might be benefited by the replacement of air entrapped with the articles within the wrapper by an atmosphere of a diflerent nature, e.g., air or a particular gas containing a higher or lower content of moisture. In the present instance, the invention will be considered from the standpoint of merely substituting an inert gas such as nitrogen for air within the wrapper so as to preserve the original fresh quality of the cheese by impeding, if not, in fact, preventing, oxidation thereof.
The sheet material within which the loaves 12 are to be wrapped is supplied to the wrapping machine 10 in the form of a continuous web 14 (FIGS. 2 and 3) pulled from a supply roll (not shown) and led upward to the intake end of a tube forming die 16. This tube former 16 presents an elongate passage open at both ends and of rectangular cross-section similar to but slightly larger than that of one of the loaves 12. The passage is defined by a horizontal bottom wall 18, vertical side walls 20, and a horizontal flange 22 projecting inward from the top of each side wall. The two flanges 22 are in coplanar alignment and cooperate to define the top wall 24 of the forming die. These flanges are only so wide that their inner edges are spaced apart slightly to define a relatively narrow slot 26 extending longitudinally of the top wall 24 of the forming die 16 throughout the full length thereof. As the web 14 feeds through the forming die 16 its side regions 28 are turned upward relatively to the midsection 30 thereof so that they line the side walls while the midsection 30 lines the bottom 28 of the forming die 16. The upper parts 32 of the side regions of the web line the flanges 22, with the lateral regions 34 turning upward through the slot 26.
At the entrance end of the forming die 16 and for a considerable distance toward the other end, the lateral edge regions 34 wrap around the inner edges of the flanges 22 and overlie the upper surfaces of the flanges in sliding engagement therewith. At this part of the forming die 16 a pair of freely rotatable tightening rollers 36 make rolling contact with the upper surfaces of the flatly lying edge regions 34. These rollers are mounted upon individual axle shafts which are inclined slightly with respect to each other so that the respective planes of rotation of the rollers converge in a downstream direction, i.e., in the direction in which the loaves 12 and the web 16 progress through the machine 10. However, in the area in which the tightener rollers 36 are located, the edge regions 34 of the web are moving inward toward the slot 26, in directions which converge at a wider angle than that between the two rollers 36. Consequently, as the edge regions 34 of the web advance under the rollers 36, the rollers tend to draw the two edge regions 34 laterally outward and thus assist in tightening the forwardly moving web 14 about the loaves 12. It is important to observe that the tube thus formed, indicated at 40 in FIGURES 2, 3 and 4, is characterized by a longitudinally extending slot 46 in the upper wall thereof due to the fact that the lateral edge regions 34 of the web do not quite come together but extend upward in spaced apart relation through the slot 26 in the top 24 of the forming die 16.
As the forwardly sliding lateral edge regions 34 approach the downstream end of the forming die 16, they are gradually turned upward from their flatly lying attitude by two upstanding tongues 42, each of which is integral with one of the flanges 22 at the inner edge thereof, as best shown in FIGURE 3. The end edges of the tongue 42 first encountered by the advancing lateral edge portions 34 of the web 14 incline upward and forward in the direction of web movement, thus to assist in the lifting and turning of the edge regions of the web to the spaced parallel arrangement in which they are shown in FIGURE 3.
The loaves of cheese 12 are delivered to the wrapping machine 10 in equally spaced apart relationship on a constantly moving endless conveyor 50 (FIGS. 1 and 2) which slides the loaves 12 successively across a short ramp 52 onto the midportion 30 of the web 14 at the place where the web is entering the forming die 16. From this region onward each loaf rests upon and is carried forward by the advancing web so that the loaf is pulled forward by the web through the forming die which turns the web upward along the sides and inward over the top of the loaf, thus wrapping the web 14 of wrapping material completely around the loaf except at its ends and where the slot 46 occurs. As the tube 40 thus formed with spaced apart loaves 12 entubed therewithin leaves the forming die, the upwardly projecting edge regions 34 of the web pass to opposite sides of a gas-jetting nozzle 56 whose cross-section is elongate in the direction of movement of the wrapper tube 40, and quite narrow transversely. Thus, gas jetted constantly from the open lower end of the nozzle 56 is directed through the slot 46 into the wrapper tube 40.
The elongate nature of the nozzle 56, measured in the direction of wrapper tube movement causes the gas to be jetted into every part of the tube for a sustained period, the duration of which corresponds to the length of time required for a given point on the wrapper tube to pass from one vertical end edge of the horizontally elongate nozzle to the other.
The nozzle 56 is carried by a head 58 having therein an elongate pressure distributing manifold passage 60 (FIG. 4) which communicates with the bore of the nozzle throughout the elongate dimension thereof through a port 62 of similarly elongate cross-section. A supply tube 64 (FIGS 1 and 2) rigidly attached to the nozzle head 58 communicates with the manifold passage 60 and with any suitable source (not shown) of the gas which it is desired to use to displace air from within the Wrapper tube.
Means are provided for determining the volume of gas that is supplied to the wrapper tube per unit of time. This may take the form of a pressure gauge 66 connected into the tube 64 since, if the characteristics of the nozzle are known, the pressure at which gas is supplied to it will be a function of the volume of gas ejected through the nozzle per unit of time. A manually operable valve 68 controlling flow through the tube 64 to the pressure gauge and to the nozzle may be regulated to obtain the pressure of the gas supplied to the nozzle which will cause the gas to be jetted into the wrapper tube in such quantities as to accomplish the eflicient purging of air from within the wrapper tube 40, as will be explained presently.
The gas-jetting nozzle 56 is supported by a pair of arms 70 (FIGS. 1, 2 and 4) to the outer ends of which the nozzle head 58 is rigidly secured. The inner ends of the arms are pivoted as by a pin 72 to a block 74 rigidly secured to a portion 76 of the frame of the wrapping machine A bracket 78 rigidly secured to the underside of the block 74 and projecting outward therefrom supports an adjusting screw 80 which is screwed through a brace 82 rigid with and extending between the two arms 70. A knurled head 84 facilitates manual operation of the adjusting screw 80 to pivot the arms 70 and nozzle 56 upward and downward so as to obtain optimum location of the nozzle 56 as far as efficiency of jetting the gas into the wrapper tube 40 is concerned.
Feeding of the wrapper tube 40 and the loaves 12 therewithin forward through the wrapping machine 10 is effected by means of an endless conveyor 90 carried by two longitudinally spaced rotary members 92, either of which may be driven while the other is an idler. These rotary members may be either pulleys or sprocket gears depending on whether the'endless conveyor 90 is of the belt type or the chain type. The upper run of the endless conveyor 90 is level with the bottom wall 18 of the forming die 16, from which the wrapping tube 40 passes across a stationary ramp plate 94 onto the upper run of the conveyor 90.
As the upstanding edge regions 34 of the wrapper tube 40 depart from the gas injection nozzle 56, they enter a relatively narrow space 100 (FIG. 1) between two elongate, longitudinally extending preheater shoes 102 which are mounted by means of an arm 104 pivoted to a support bracket 106 rigid with the frame member 76. A flange member 108 of the bracket 106 projects outward from the frame member 76 in position to engage the under surface of the arm 104 and thus support the arm and preheater shoes 102 in optimum position for the edge portions 34 of the wrapper tube web to pass through the slot 100 as the wrapper tube progresses through the wrapping machine 10.
The preheater shoes 102 are kept at such temperature that as the edge portions 34 pass therebetween, they are heated to such an extent that the thermoplastic material of which the web is made becomes tacky so that when the edge portions 34 are pressed together they will become welded and thus establish the longitudinal seal of the wrapper tube. Preferably such heating of the edge portions 34 is effected by radiation and conduction only, inasmuch as it is desired to keep the edge portions out of direct physical contact with the heater shoes because the heating of the edge portions 34 to the desired temperature can be more readily regulated and maintained uniform if such direct contact is avoided.
The pivotal mounting of the support arm 104 for the preheater shoes permits the shoes to be raised when the wrapping machine 10 is being readied for operation and the wrapper tube is being threaded therethrough. The preheater shoes 102 are heated by electrical resistance elements (not shown) embedded within them and supplied with electrical energy through any suitable control mechanism (not shown) and from any suitable source (not shown).
Immediately beyond the preheater shoes 102 are a pair of sealing wheels, or pressure rollers 110 journalled in a bracket 112 for rotation about vertical axes. The two sealing rollers 110 are interconnected for simultaneous rotation in opposite directions by means of meshing gears 114 each of which is rigid with the shaft 116 of one of the sealing wheels 110. A bevel gear 118 on one of the shafts 116 meshes with a bevel gear 120 carried by a drive shaft 122 journalled in frame member 76 and projecting therethrough for connection to a suitable drive mechanism (not shown) The sealing rollers 110 are so positioned that the bite therebetween is in longitudinal alignment with the space between the preheater shoes 102, thus permitting the heated upstanding edge portions 34 of the wrapper tube to pass directly from between the preheater shoes 102 into the bite between the sealing rollers which, therefore, press the edge portions 34 tightly together and thus weld the lateral edges of the wrapper tube 14 together in a longitudinal seal. Thus an upstanding fin 124 is formed which shortly thereafter encounters a camming shoe or plow 126 rigidly supported by a bracket 128 (FIG. 1) secured to the frame member 76. The camming shoe 126 turns the fin 124 down against the upper surface of the wrapper tube as it advances therepast, to facilitate smooth entry of the formed tube between upper and lower transverse sealing rollers 130 of known design and driven and synchronized with the loaf spacing conveyor 50 as fully explained in the aforementioned Patent No. 2,602,- 276, so that the rollers 130 flatten the wrapper tube 40 by pressing the upper and lower walls of the tube together between each two adjacent loaves 12 as the tube with the loaves therein passes between the transverse sealing rollers. Moreover, the sealing rollers 130 are provided with sealing means (not shown) and severing means (not shown) as is also clearly explained in the aforesaid Patent No. 2,602,276, so that each loaf is sealed individually within a package 132 whose wrapping consists of a suitable length of the web 14 of wrapping material, and within which substantially all air has been replaced by an inert gas.
It will be understood that the wrapping material employed is a flexible sheet of gas-impervious thermoplastic material. A number of such materials suitable for this use are available, among them being those known as Pliofilm, and Vinylite and Paracote.
From the above description it will be understood that as the wrapper tube 40 with the spaced apart loaves 12 of cheese entubed therewithin passes out of the forming die 16, the longitudinally extending groove 46 in the top wall of the wrapper tube is open, thus establishing communication between the interior and the exterior of the wrapper tube 40. As the wrapper tube progresses past the gas-jetting nozzle 56, this open groove comes into register with the nozzle so that the gas jetted from the nozzle is directed under considerable force into the interior of the wrapper tube. In this manner the gas is caused to displace at least the major portion of the air which has been entrapped within the tube 40 along with the loaves 12 as the tube is constructed within the forming die 16. It has been found that removal .of the air from within the wrapper tube by means of the apparatus described is highly efficient, one factor contributing toward such efficient operation being the elongate nature of the jetting nozzle 56 measured in the direction of wrapper tube advance. Additionally, the gas is jetted into the wrapper tube in considerable quantity. The two factors cause a body, or wall, of the inert gas to develop within the wrapper tube within the region of the jetting nozzle 56. Whereas this wall of the inert gas is probably not well defined because of the tendency of it to mingle with the air being carried toward and into it by the advancing wrapper tube 14 and the articles therewithin, it does nevertheless function more or less in the nature of a plug lying in the path of the oncoming air within the tube, that blocks continued passage of the air toward and past the region where the inert gas is injected. Furthermore, the quantity of the inert gas which injected into the wrapper tube is considerably in excess of that which is necessary to fill all of the space within the wrapper tube 40 which is not occupied by the loaves of cheese. Some of this excess quantity, of course, will escape from the tube downstream from the jetting nozzle 56, i.e. before the lateral edges of the wrapper tube reach and are sealed together by the sealing rollers 110. Nevertheless a substantial quantity of the excess inert gas will flow in the opposite direction from the jetting nozzle 56 thus causing the air approaching the so-called gaseous plug of inert gas to be swept out of the wrapper tube through the slot 46 in that region of the tube which is approaching the jetting nozzle 56.
As the completed packages 132 are discharged from the wrapping machine 10, practically all of the air has been removed from the part of the wrapper tube of which the wrapping of each package is composed, and in the place of the air the package contains the inert gas. Thus conditions are established within the completed package which are most conducive to preservation of the wrapped cheese in optimum conditions with respect to both the fresh or unoxidized character of the product and to its moisture content, as well as the appearance of the package which is an important factor from the standpoint of marketability inasmuch as such packages are usually offered for sale in open-topped refrigerator cases where they are exposed to the view of the purchasing public.
Whereas the invention has been described as employing nitrogen as the inert gas to be used in replacing the air within the wrapper tube, it is to be understood that other inert gases may be resorted to, the particular gas selected depending, of course, upon the nature of the product to be wrapped and the condition to be maintained in the completed packages thereof. For example, carbon dioxide is another inert gas suitable for this use under some circumstances.
While apparatus constituting a particular embodiment of the invention and a particular series of steps embodying the method of the invention has been shown and described, it will be understood that the apparatus and the method are capable of modification and variation without de parting from the principles of the invention and that the scope of the invention should be limited only by the scope and proper interpretation of the claims appended hereto.
The invention having thus been described what is believed to be new and desired to be protected by Letters Patent is:
1. A wrapping machine comprising a tube forming die, said die having a horizontal, longitudinally extending base wall and laterally spaced side walls, each side wall having one edge connected to and projecting vertically from the associated edge of said horizontal base Wall, the other edges of said side walls being first inclined away from said base wall and then extending horizontally and vertically spaced from said base wall, horizontal flanges projecting toward each other from the horizontal portions of said other edges of the side walls, the op posed free edges of said horizontal flanges first converging toward one another to form a V-shaped channel, and then continuing in a generally parallel spaced relation to form a longitudinal slot, means at each of said horizontal flanges adjacent the apex of said V-shaped channel for camming the lateral edge regions of said web, means upstream of said camming means for pressing the lateral edge regions of the web against the outer faces of said horizontal die flanges, a thin horizontally extending and vertically disposed gas injection nozzle longitudinally aligned with said slot in the tube forming die, the gas emitting edge of said nozzle lying substantially in the plane of the horizontal flanges of said tube forming die, means for advancing a web of wrapping material and the articles to be wrapped through said tube forming die with said die causing said web to conform to an article within the die to form a tube, with the lateral edge portions of the web overlying said horizontal flanges of the die, said pressing means locally holding the lateral edge regions of the web against the outer faces of the horizontal flanges of the die, said camming means thereafter camming the lateral edge regions of the web into vertical, laterally spaced web flanges for straddling said nozzle as the tube advances, and means downstream of said nozzle for sealing said web flanges together.
2. The machine of claim 1 wherein said means for camming the lateral edge regions of said web into vertically disposed flanges comprises laterally spaced tongues projecting vertically from said horizontal die flanges adjacent the apex of said V-shaped channel, the upstream edges of said tongues being inclined from the horizontal away from said horizontal die flanges.
3. The machine of claim 1, wherein said means for pressing the lateral edge regions of the web against said horizontal die flanges comprises a pair of laterally opposed rollers that converge in the downstream direction.
4. The machine of claim 1, wherein laterally spaced, elongate preheater shoes are mounted between said gas nozzle and said web flange sealing means, said shoes providing a longitudinal slot aligned with said forming die slot for receiving said vertical flanges before they are carried through said tube flange sealing means.
References Cited by the Examiner UNITED STATES PATENTS 2,565,444 8/51 Waters 53-112 2,863,266 12/58 Moore 5322 2,919,990 1/60 Podlesak et al. 53112 FOREIGN PATENTS 1,257,114 2/61 France.
FRANK E. BAILEY, Primary Examiner.